<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python documentation Index' />
<link rel="first" href="lib.html" title='Python library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="profile-instant.html" />
<link rel="prev" href="profile.html" />
<link rel="parent" href="profile.html" />
<link rel="next" href="profile-instant.html" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name='aesop' content='information' />
<title>25.1 Introduction to the profilers</title>
</head>
<body>
<div class="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="25. the Python Profilers"
  href="profile.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="25. the Python Profilers"
  href="profile.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="25.2 instant User's Manual"
  href="profile-instant.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="profile.html">25. The Python Profilers</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="profile.html">25. The Python Profilers</a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="profile-instant.html">25.2 Instant User's Manual</a>
</div>
<hr /></div>
</div>
<!--End of Navigation Panel-->

<h1><a name="SECTION0027100000000000000000">
25.1 Introduction to the profilers</a>
</h1>
<a name="Profiler_Introduction"></a>
<p>
A <i class="dfn">profiler</i> is a program that describes the run time performance
of a program, providing a variety of statistics.  This documentation
describes the profiler functionality provided in the modules
<tt class="module">profile</tt> and <tt class="module">pstats</tt>.  This profiler provides
<i class="dfn">deterministic profiling</i> of any Python programs.  It also
provides a series of report generation tools to allow users to rapidly
examine the results of a profile operation.
<a id='l2h-5090' xml:id='l2h-5090'></a>

<p>
The Python standard library provides three different profilers:

<p>

<ol>
<li><tt class="module">profile</tt>, a pure Python module, described in the sequel.
  Copyright © 1994, by InfoSeek Corporation.
  
<span class="versionnote">Changed in version 2.4:
also reports the time spent in calls to built-in
  functions and methods.</span>

<p>
</li>
<li><tt class="module">cProfile</tt>, a module written in C, with a reasonable
  overhead that makes it suitable for profiling long-running programs.
  Based on <tt class="module">lsprof</tt>, contributed by Brett Rosen and Ted Czotter.
  
<span class="versionnote">New in version 2.5.</span>

<p>
</li>
<li><tt class="module">hotshot</tt>, a C module focusing on minimizing the overhead
  while profiling, at the expense of long data post-processing times.
  
<span class="versionnote">Changed in version 2.5:
the results should be more meaningful than in the
  past: the timing core contained a critical bug.</span>

</li>
</ol>

<p>
The <tt class="module">profile</tt> and <tt class="module">cProfile</tt> modules export the same
interface, so they are mostly interchangeables; <tt class="module">cProfile</tt> has a
much lower overhead but is not so far as well-tested and might not be
available on all systems.  <tt class="module">cProfile</tt> is really a compatibility
layer on top of the internal <tt class="module">_lsprof</tt> module.  The
<tt class="module">hotshot</tt> module is reserved to specialized usages.

<p>

<div class="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="25. the Python Profilers"
  href="profile.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="25. the Python Profilers"
  href="profile.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="25.2 instant User's Manual"
  href="profile-instant.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="profile.html">25. The Python Profilers</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="profile.html">25. The Python Profilers</a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="profile-instant.html">25.2 Instant User's Manual</a>
</div>
</div>
<hr />
<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
</div>
<!--End of Navigation Panel-->
<address>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</address>
</body>
</html>
